During operation of a washing machine, an unbalanced load of clothes or other articles may cause the basket to spin or rotate off-axis and may cause the tub containing the basket to vibrate. The vibration excursions tend to be especially acute during the start of the spin cycle. At the beginning of the spin cycle, the excursions may become large enough, as the machine passes through resonance of the suspension, for the tub to bang against the washer housing. Accordingly, it would be highly desirable to have a vibration damper that is responsive to the low frequency, high magnitude=excursions normally present at the beginning of the spin cycle to minimize the excursions.
As the washer spin cycle progresses, the rotational speed of the basket increases, and the excursions tend to be limited because the clothes redistribute themselves and because the machine is operating above the resonant speed of the suspension. Stiffening the suspension will keep the tub aligned, but permanently stiffening the suspension will increase the suspension frequency causing the machine to pass through resonance at a higher, more damaging, speed. Accordingly, it would be highly desirable to have a vibration damper that limits the excursions and/or temporarily stiffens the washer suspension to keep the tub aligned.